Tapeworms are one of the oldest known parasites, and fossilized remains of them have been found in shark feces dating back 270 million years. No one examines ancient shark poop without hoping to find something. (We might do well to consider humble scientists looking for tapeworms in prehistoric shark poop while the rest of us are out living our lives.)
The tapeworm attaches its scolex, or head, to the intestinal wall and pulls out nutrients. As it eats, it forms little sections called proglottids. Each proglottid functions like a separate individual with its own digestive and reproductive system; moreover, each proglottid is hermaphroditic, meaning it can mate with itself, saving the trouble of trying to meet other tapeworms. This is a good thing for the tapeworm, because, living in the intestine as it does, it doesn't get out much. As the tapeworm grows, older sections are pushed to the end of the tail, until they finally detach, being, at that point, essentially just a sackful of eggs, and the miracle of birth begins anew.
Everyone always talks glowingly about the cycle of life, but they're always thinking about lions and things; no one ever mentions tapeworms, and I think it's high time someone did. So here's to the humble tapeworm, silent and hidden, feeding away and dreaming its little proglottids will one day have children of their own, serving - I'm sure - its own part in God's mysterious scheme.
